Abstract:
Three different types of geopolymer cement from granulated blast furnace
slag (GBFS), pulverized fly ash (FA) and silica fume (SF) were prepared. The cements were activated by sodium hydroxide (SH) and water
glass (WG) which were dissolved in mixing water. The hydration characteristics
of the different cement mixes were measured including water of
consistency (W/C) ratio, setting times, bulk density, apparent porosity,
bound water content and compressive strength. The W/C ratio increased
as the amount of NaOH increased. It also increased with addition of either
FA or SF. The bound water content of the alkali-activated GBFS cement
pastes gradually increased at all hydration times. The bulk density
improved whilst apparent porosity declined. This had a positive effect
on compressive strength. The results demonstrated that 90 % GBFS and
10 % Silica Fume activated by 1.0 mol/kg water glass and 3.0 M NaOH
had reasonable and satisfactory hydration properties and was the most
appropriate binding material. It is a sustainable binding material that
can be successfully used as an alternative to ordinary Portland cement.